Stanley Vivian

Pituitary hormone releasing or inhibiting activity of metal ions present in hypothalamic extracts.

Abstract In vitro trophin-releasing and inhibiting activities of certain purified fractions from bovine hypothalamus were apparently due primarily to the presence of divalent metals. The most abundant metal was copper which at concentrations less than 1 μg/ml markedly stimulated the release of all hormones. Zinc ion which was much less potent than copper, inhibited release of prolactin but stimulated release of the other hormones. Nickel, as low as 1 μg/ml, specifically inhibited prolcatin release; at much higher levels it enhanced release of the other hormones.

Prolactin secretion is specifically inhibited by nickel.

PROLACTIN (PRL) secretion from the mammalian anterior pituitary gland is apparently chiefly under hypothalamic tonic inhibition in contrast to the primarily stimulatory influence of the brain on the other trophic hormones1. Extracts of mammalian hypothalamus inhibit the release of PRL in vitro and in vivo1. We report here that PRL-inhibiting-factor (PIF) activity in certain fractions derived from acetic acid extracts of bovine hypothalamus was due to nickel ion (Ni2+) in the extracts. Commercial nickel salts and purified PIF from bovine brain specifically inhibit release of PRL in vivo in the rat and in vitro from bovine pituitary, (a) in basal conditions, (b) in the presence of copper ion which markedly enhances release of all trophic hormones, and (c) following brief exposure of the pituitary tissue to cold, another effective, non-specific stimulant of hormone release.

Amino acid composition of elastin in the developing human aorta

Abstract Elastin was prepared by alkali extraction of defatted human thoracic aortas from 14-, 23-, and 33-week-old fetuses and individuals aged 5 months and 1, 5, 10 and 51 years. The content of lysine decreased and that of desmosines and lysinonorleucine increased most markedly in fetal elastin. Several unknown ninhydrin-positive substances emerged in the basic region of the chromatogram. Two of these unknowns, eluted just after lysine, were incompletely resolved from each other and together comprised 9.6 residues per 1000 total residues in 14-week fetal elastin, decreasing to 8.3 at 23 weeks, to 2.5 residues at 33 weeks, and thereafter were present only in traces. Tyrosine increased in fetal elastin from 7.2 residues at 14 weeks to 11 at 23 weeks and to the adult level of 19 at 33 weeks. Certain other polar amino acids appeared to decrease in elastin with age. Individual variation in the amino acid composition of elastin appears to reside mainly in the relative proportions of glycine, alanine, and proline which make up exactly two-thirds of the total residues.

Effect of B-aminopropionitrile or prednisolone on survival of male LAF/J mice

Abstract Authors examined the effects of B -aminopropionitrile (BAPN) and prednisolone, added to the drinking water at 1 mg/ml and 2μg/ml, respectively, on survival of 2-month old male LAF/J mice. In one experiment BAPN, prednisolone, or both were administered throughout the entire lifespan, with no significant differences from control in either mean lifespan, 28–29 months, or maximum lifespan, 33–35 months. In a second experiment, BAPN was administered for 0, 3, 6, 9 or 12 months only. Median lifespan of 26 months for control animals was significantly increased for 3 of the 4 test groups, the animals treated with BAPN for 12 months showing the greatest increase, i.e. median 31 months. Maximum lifespan of control animals was 33 months, and was 1–3 months longer for BAPN treated groups.